CN114829799A

CN114829799A - Disc brake

Info

Publication number: CN114829799A
Application number: CN202080087616.0A
Authority: CN
Inventors: 俞昊; 臼井拓也
Original assignee: Hitachi Astemo Ltd
Current assignee: Hitachi Astemo Ltd
Priority date: 2019-12-25
Filing date: 2020-12-10
Publication date: 2022-07-29
Also published as: WO2021131736A1; KR20220091556A; JPWO2021131736A1; US20230044286A1; JP7394149B2; DE112020006393T5

Abstract

A disc brake is provided with: a brake mechanism that advances a piston in a cylinder portion by driving of an electric motor, and applies a braking force by pressing an inner brake pad and an outer brake pad against a disc rotor; and an elastic member that biases the inner brake pad and the outer brake pad in a direction away from the disc rotor in an axial direction of the disc rotor, the biasing force of the elastic member being set to be larger than a sliding resistance of the piston with respect to the cylinder portion. This can effectively suppress dragging of the inner and outer brake pads.

Description

Disc brake

Technical Field

The present invention relates to a disc brake for braking of a vehicle.

Background

In a conventional disc brake, a disc brake device described in patent document 1 has been proposed as a structure for suppressing dragging of pads. In the disc brake device described in patent document 1, a disc spring is provided for returning a piston slidably fitted in a cylinder portion in an axial direction in the axial direction. As a result, when the brake operation is released, the piston is returned in the axial direction against the frictional engagement force generated between the piston and the wall surface of the cylinder portion by the biasing force of the disc spring. This allows the inner pad to be easily separated from the disc rotor, and suppresses a drag phenomenon of the inner pad, i.e., drag torque.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-68977

Disclosure of Invention

Problems to be solved by the invention

However, in the disc brake device described in patent document 1, the pad does not include the return mechanism, and therefore, the drag torque reduction effect is small. In addition, in general, the disc brake needs to include a pad wear following mechanism that advances the piston in accordance with the wear of the pad, but the disc brake device described in patent document 1 has a complicated structure.

Another object of the present invention is to provide a disc brake capable of effectively suppressing dragging of pads.

Means for solving the problems

A first aspect of the present invention is a disc brake including: a brake mechanism that pushes a piston in a cylinder portion by driving of an electric motor and applies a braking force by pressing a pad against a disc rotor; and an elastic member that biases the pad in a direction away from the disc rotor in an axial direction of the disc rotor, the elastic member having a biasing force larger than a sliding resistance of the piston with respect to the cylinder portion.

A second aspect of the present invention is a disc brake including: a brake mechanism including a mounting member that supports sliding of a pad and is mounted to a non-rotating portion of a vehicle, and a caliper that has a cylinder portion and is supported so as to be slidable in an axial direction of a disc rotor with respect to the mounting member, the brake mechanism pressing the pad against the disc rotor by a piston that slides in the cylinder portion to apply a braking force; and an elastic member that biases the pad in a direction away from the disc rotor in an axial direction of the disc rotor, the elastic member having a biasing force smaller than a sliding resistance of the piston with respect to the cylinder portion and larger than a force obtained by adding the sliding resistance of the pad with respect to the mounting member and the sliding resistance of the caliper with respect to the mounting member.

According to the disc brake of the embodiment of the present invention, dragging of the pad can be effectively suppressed.

Drawings

Fig. 1 is a perspective view of a disc brake according to an embodiment of the present invention.

Fig. 2 is a partial sectional view of a disc brake according to an embodiment of the present invention.

Fig. 3 is an exploded perspective view of a main part of a disc brake according to an embodiment of the present invention.

Fig. 4 is a perspective view of an elastic member used in the disc brake according to the embodiment of the present invention.

Detailed Description

The present embodiment will be described in detail below with reference to fig. 1 to 4.

As shown in fig. 1 to 3, the disc brake 1 according to the embodiment of the present invention employs an electric brake device that generates a braking force by driving an electric motor 56. The disc brake 1 is provided with: a pair of inner brake pads 2 and outer brake pads 3 disposed on both sides in the axial direction of a disc rotor D attached to a rotating portion (not shown) of a vehicle with the disc rotor D interposed therebetween; and a brake caliper 4. The disc brake 1 is configured as a caliper floating type. The pair of inner and

outer brake pads

2, 3 and the caliper 4 are supported by a bracket 5 so as to be movable in the axial direction of the disc rotor D, and the bracket 5 is fixed to a non-rotating portion (not shown) such as a knuckle of a vehicle. The bracket 5 corresponds to a mounting member.

The bracket 5 includes: a pair of

pin insertion portions

8, 8 into which

slide pins

64, 64 described later are inserted, respectively; and an inner side support portion 9 and an outer side support portion 10 integrally connected to the pair of

pin insertion portions

8, 8 and supporting the inner brake pad 2 and the outer brake pad 3, respectively, independently. The pair of

pin insertion portions

8, 8 are disposed at intervals along the rotational direction of the disc rotor D. The pair of

pin insertion portions

8, 8 each extend in the axial direction of the disc rotor D. Each pin insertion portion 8 is formed in a bottomed cylindrical shape. The slide pin 64 is inserted into each pin insertion portion 8 so as to be slidable in the axial direction.

The opening side of each pin insertion portion 8 is directed inward, and the bottom side thereof is directed outward. Cylindrical pin

hole boss portions

11 and 11 are formed at the inner end of each pin insertion portion 8. An outer support portion 10 is integrally connected to the outer side of each pin insertion portion 8. Further, an inner support portion 9 is connected to each pin insertion portion 8 at a distance from the outer support portion 10 inward in the axial direction of the disc rotor D.

The inner support portion 9 is composed of a pair of

inner arm portions

14, 14 extending from the pair of

pin insertion portions

8, 8 in substantially orthogonal directions, and an inner beam portion 15 connecting end portions of the pair of

inner arm portions

14, 14. Fitting

recesses

16, 16 are formed in the facing surfaces of the pair of inner arm portions 14, respectively. The

fitting recesses

16, 16 are formed along the axial direction of the disc rotor D. The pad spring 31 is fitted to the fitting recess 16 of the inner arm portion 14 and the fitting recess 19 of the outer support portion 10 (outer arm portion 17) described later so as to straddle them. Through

holes

22, 22 penetrating in the axial direction of the disc rotor D are formed in both ends of the inner beam portion 15 in the rotational direction of the disc rotor D.

The inner brake pad 2 includes: the inner liner 24 that receives frictional force by contact with the disc rotor D; an inner back plate 25 provided on the back surface of the inner liner 24 opposite to the surface in contact with the disk rotor D; and an inner pad 26 provided on the back surface of the inner back panel 25 opposite to the surface in contact with the inner liner 24. The inner back plate 25 has fitting

portions

29, 29 formed at both ends in the rotational direction of the disc rotor D and projecting outward therefrom, respectively. Fixing

boss portions

30, 30 for fixing

elastic members

34, 34 described later are provided around the

fitting portions

29, 29 so as to protrude inward.

The inner brake pad 2 is disposed between the pair of

inner arm portions

14, 14 by fitting the respective

fitting portions

29, 29 of the inner back plate 25 into the respective fitting

concave portions

16, 16 provided on the facing surfaces of the pair of

inner arm portions

14, 14 via the

pad springs

31, 31. As a result, the inner brake pad 2 is supported slidably in the axial direction of the disc rotor D with respect to the pair of

inner arm portions

14, 14. Here, at the time of braking and at the time of brake release, sliding resistance of the inner brake pad 2 with respect to the pair of

inner arm portions

14, 14 is generated.

The elastic member 34 is disposed between the inner brake pad 2, specifically, the inner back plate 25 and the inner support portion 9 of the carrier 5. The

elastic members

34, 34 are arranged in a pair at an interval in the rotation direction of the disk rotor D. The pair of

elastic members

34, 34 urge the inner brake pad 2 inward in the axial direction of the disc rotor D, that is, in a direction away from the disc rotor D. In other words, the pair of

elastic members

34 and 34 urge the inner brake pad 2 in a direction away from the disc rotor D with respect to the inner support portion 9 of the carrier 5. As shown in fig. 4, referring also to fig. 2, the elastic member 34 is formed by bending a thin, long, substantially rectangular spring plate material at a plurality of locations. In detail, the elastic member 34 is composed of: a fixing portion 37 fixed to a boss portion 30 for fixing provided on the inner back plate 25 of the inner brake pad 2; an upright portion 38 continuously extending from an end of the fixing portion 37; an inclined portion 39 continuously extending from an end of the standing portion 38; an opposing portion 40 continuously extending from the inclined portion 39; and a contact portion 41 continuously extending from an end of the facing portion 40.

The fixing portion 37 is formed with a fixing hole 42 for fixing the elastic member 34 to the fixing boss portion 30 of the inner back plate 25. The standing portion 38 extends from an end of the fixing portion 37 substantially perpendicularly to the fixing portion 37. The standing portion 38 extends in a direction away from the fixing portion 37 (inner back plate 25). The inclined portion 39 extends from the end of the standing portion 38 toward the inner arm portion 14 in the attached state of the elastic member 34. The inclined portion 39 extends obliquely with respect to the longitudinal direction of the inner brake pad 2 so as to approach the inner arm portion 14 in the attached state of the elastic member 34. The facing portion 40 extends to face the standing portion 38. The facing portion 40 extends slightly obliquely inward with respect to the axial direction of the disc rotor D in the attached state of the elastic member 34. In other words, the facing portion 40 extends obliquely so that the distance from the standing portion 38 gradually decreases. The contact portion 41 extends while being bent in a semicircular arc shape outward in the attached state of the elastic member 34. In the attached state of the elastic member 34, the outer peripheral surface of the contact portion 41 contacts the inner surface of the inner arm portion 14.

The fixing holes 42 provided in the fixing portions 37 of the elastic members 34 are inserted into the fixing boss portions 30 provided in the inner back plate 25 of the inner brake pad 2, and the pair of

elastic members

34, 34 are fixed to the inner back plate 25. At this time, the outer peripheral surfaces of the

contact portions

41, 41 of the

elastic members

34, 34 are in contact with the inner surfaces of the

inner arm portions

14, 14 of the bracket 5, respectively. As a result, the inner brake pad 2 is biased inward, i.e., away from the disc rotor D, with respect to the inner support portion 9 in the axial direction of the disc rotor D by the

elastic members

34, 34.

The outer support portion 10 is composed of a pair of

outer arm portions

17, 17 extending from the

pin insertion portions

8, 8 in substantially orthogonal directions, and an outer beam portion 18 connecting end portions of the pair of

outer arm portions

17, 17. Fitting recesses 19, 19 are formed in the facing surfaces of the pair of outer arm portions 17, respectively. The fitting recesses 19, 19 are formed along the axial direction of the disc rotor D. As described above, the pad spring 31 is fitted to the fitting recess 16 of the inner support portion 9 (inner arm portion 14) and the fitting recess 19 of the outer arm portion 17 so as to straddle them. The bracket 5 is attached to a non-rotating portion of the vehicle via through

holes

22, 22 provided in the inner support portion 9 (inner beam portion 15).

The outer brake pad 3 is configured to include, similarly to the inner brake pad 2: an outer liner 44 that receives a frictional force by contact with the disk rotor D; an outer back plate 45 provided on the back surface of the outer liner 44 opposite to the surface in contact with the disk rotor D; and an outer pad 46 provided on the back surface of the outer back plate 45 opposite to the surface in contact with the outer lining 44. The outer back plate 45 has

fitting portions

49, 49 projecting outward at both ends in the rotational direction of the disc rotor D.

Fixing boss portions

50, 50 for fixing the

elastic members

34, 34 are provided around the

fitting portions

49, 49 so as to protrude outward.

The outer brake pad 3 is disposed between the pair of

outer arm portions

17, 17 by fitting the respective

fitting portions

49, 49 of the outer back plate 45 to the respective fitting recesses 19, 19 provided in the facing surfaces of the pair of

outer arm portions

17, 17 via the pad springs 31, 31. As a result, the outer brake pad 3 is supported slidably in the axial direction of the disc rotor D with respect to the pair of

outer arm portions

17, 17. Here, at the time of braking and at the time of brake release, sliding resistance of the outer brake pad 3 with respect to the pair of

outer arm portions

17, 17 is generated.

The elastic member 34 is disposed between the outer brake pad 3, more specifically, the outer backing plate 45 and the outer support portion 10 of the carrier 5. The

elastic members

34, 34 urge the outer brake pad 3 outward in the axial direction of the disc rotor D, that is, in a direction away from the disc rotor D. In other words, the pair of

elastic members

34 and 34 urge the outer brake pad 3 in a direction away from the disc rotor D with respect to the outer support portion 10 of the carrier 5. The configuration of the outer elastic member 34 is the same as that of the inner elastic member 34 provided between the inner brake pad 2 and the carrier 5, and therefore, the description thereof is omitted.

The fixing holes 42 provided in the fixing portions 37 of the elastic members 34 are inserted into the respective fixing boss portions 50 provided in the outer back plate 45 of the outer brake pad 3, and the pair of

elastic members

34, 34 are fixed to the outer back plate 45, respectively. At this time, the outer peripheral surfaces of the

contact portions

41 and 41 of the

elastic members

34 and 34 are in contact with the outer surfaces of the outer arm portions 15 of the bracket 5, respectively. As a result, the outer brake pad 3 is biased outward, i.e., away from the disc rotor D, with respect to the outer support portion 10 in the axial direction of the disc rotor D by the respective

elastic members

34, 34. The urging force of the elastic member 34 will be described in detail later.

As shown in fig. 1 and 2, the caliper 4 includes a caliper main body 55 as a main body of the caliper 4, and an electric motor 56 arranged in line with the caliper main body 55. A cylindrical cylinder portion 59, a pair of claw portions 60, and a pair of

caliper arm portions

61, 61 are integrally connected to the caliper main body 55, the cylindrical cylinder portion 59 is disposed on a base end side facing the inner brake pad 2 on the vehicle inner side and is open facing the inner brake pad 2, the pair of

claw portions

60, 60 extend outward from the cylinder portion 59 across the disc rotor D and are disposed on a tip end side facing the outer brake pad 3 on the vehicle outer side, and the pair of

caliper arm portions

61, 61 extend outward from the cylinder portion 59.

Slide pins 64, 64 are fixed to the tip end portions of the pair of

caliper arm portions

61, 61 by respective fixing

nuts

65, 65. The slide pins 64, 64 extend in the axial direction of the cylinder portion 59. As described above, the slide pins 64 and 64 extending from the cylinder portion 59 are inserted into the pair of

pin insertion portions

8 and 8 of the bracket 5 so as to be slidable in the axial direction. Here, at the time of braking and at the time of brake release, sliding resistance of the respective slide pins 64, 64 with respect to the respective

pin insertion portions

8, 8 is generated. Rubber pin protection covers 66, 66 having bellows portions that can be extended and contracted and that cover the slide pins 64, 64 are provided between the

caliper arms

61, 61 of the caliper main body 55 and the

pin insertion portions

8, 8 of the bracket 5.

Referring to fig. 2, a cylinder bore 70 is formed inside the cylinder portion 59. A piston 72 is disposed slidably in the axial direction in the cylinder bore 70 of the cylinder portion 59. A seal member (not shown) is disposed between the outer peripheral surface of the piston 72 and the inner peripheral surface of the cylinder bore 70. The piston 72 is formed in a cup shape for pressing the inner brake pad 2. The bottom portion 54 of the piston 72 is disposed in the cylinder bore 70 so as to face the inner brake pad 2. The bottom portion 54 of the piston 72 and the inner brake pad 2 are engaged together so as not to be able to rotate relative to each other. By this engagement, the piston 72 is not rotatable relative to the cylinder bore 70 and hence relative to the caliper main body 55. Here, at the time of braking and at the time of brake release, sliding resistance of the piston 72 with respect to the cylinder bore 70 is generated.

The caliper main body 55 includes a brake mechanism 76 and a control device 79. The braking mechanism 76 includes: a speed reduction mechanism 74 for reducing the speed of rotation of the electric motor 56 and increasing the torque thereof; and a rotation-to-linear motion conversion mechanism 75 that applies thrust to the piston 72 by transmitting rotation from the speed reduction mechanism 74. The speed reduction mechanism 74 includes a planetary gear speed reduction mechanism or the like to which the rotation from the electric motor 56 is transmitted, and the rotation from the electric motor 56 is reduced in speed and increased in force by the speed reduction mechanism 74 and transmitted to the rotation-to-linear motion conversion mechanism 75.

Although not shown, the rotation-to-linear motion converting mechanism 75 is configured to include, for example, a member (rotating member) for transmitting a rotation shaft from the speed reducing mechanism 74 and a nut member (linear motion member) threadedly engaged with the shaft member. That is, the shaft member of the rotation-to-linear conversion mechanism 75 is supported so as not to be movable in the axial direction, and the nut member is supported so as to be movable in the axial direction and is supported so as not to be rotatable relative to the cylinder portion 59. When the rotation/translation mechanism 75 is operated, the nut member is translated by the rotation of the shaft member, and presses the piston 72.

Although not shown, the rotation-to-linear motion conversion mechanism 75 is configured to include, for example, a shaft member (rotation-to-linear motion member) to which a rotation shaft from the speed reduction mechanism 74 is transmitted and a nut member (fixing member) that is threadedly engaged with the shaft member, but the shaft member is supported rotatably with respect to the cylinder portion 59 and movably in the axial direction. On the other hand, the nut member is supported so as not to be rotatable relative to the cylinder portion 59 and so as not to be movable in the axial direction. When the rotation/translation mechanism 75 is operated, the shaft member moves linearly while rotating relative to the nut member, and presses the piston 72.

When the rotation-to-linear conversion mechanism 75 is operated during braking and during brake release, sliding resistance is generated at the screw engagement portion between the shaft member and the nut member.

The control device 79 controls the driving force of the electric motor 56 based on the position information of the piston 72. More specifically, although not shown, a rotation angle detection means for detecting the rotation angle of the electric motor 56, a thrust sensor for detecting a reaction force when the disc rotor D is pressed by the inner brake pad 2 and the outer brake pad 3, a detection sensor for detecting a request of the driver such as a stroke sensor attached to a brake pedal, and various detection sensors for detecting various situations in which the driver is not required to apply the brake are electrically connected to the control device 79. During braking and when the brake is released during normal traveling, the control device 79 controls the driving of the electric motor 56 based on the detection signal from the rotation angle detection means, that is, the position information of the piston 72, the detection signal from the thrust sensor, the detection sensor corresponding to the request of the driver, the detection signals from various detection sensors that detect various conditions requiring braking, and the like, thereby controlling the position of the linear motion member (including the rotational linear motion member) of the rotational/linear motion conversion mechanism 75 in the axial direction within the cylinder portion 59.

The biasing force of each elastic member 34 is set to be larger than the sliding resistance of the inner brake pad 2 and the outer brake pad 3 with respect to the inner arm portion 14 and the outer arm portion 17 of the carrier 5. The urging force of each elastic member 34 is set to be larger than the sliding resistance of the piston 72 with respect to the cylinder bore 70 of the cylinder portion 59. The urging force of each elastic member 34 is set to be larger than the sliding resistance of each

slide pin

64, 64 coupled to the cylinder portion 59 with respect to each

pin insertion portion

8, 8 of the bracket 5. The urging force of each elastic member 34 is set to be larger than the sliding resistance obtained by adding the sliding resistance of the piston 72 to the cylinder bore 70 of the cylinder portion 59 to the sliding resistance of the inner brake pad 2 and the outer brake pad 3 to the inner arm portion 14 and the outer arm portion 17. The urging force of each elastic member 34 is set to be smaller than the sliding resistance for operating the rotation-to-linear conversion mechanism 75. The urging force of each elastic member 34 may be set to be smaller than the sliding resistance of the piston 72 with respect to the cylinder portion 59 and larger than a force obtained by adding the sliding resistance of the inner brake pad 2 and the outer brake pad 3 with respect to the inner arm portion 14 and the outer arm portion 17 of the bracket 5 and the sliding resistance of each

slide pin

64, 64 connected to the cylinder portion 59 with respect to each

pin insertion portion

8, 8 of the bracket 5.

Next, the disc brake 1 according to the present embodiment described above will be described with respect to braking during normal running and an operation at the time of brake release.

During braking during normal traveling, the electric motor 56 is driven in accordance with a command from the control device 79, and the rotation in the braking direction is transmitted to the rotation-to-linear motion conversion mechanism 75 via the speed reduction mechanism 74. As a result, the linear motion member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 advances, and the piston 72 advances. Then, the piston 72 presses the inner brake pad 2 against the disc rotor D while elastically deforming the seal member with the cylinder bore 70. Next, the caliper main body 55 is moved in the rightward direction in fig. 2 with respect to the carrier 5 by a reaction force against the pressing force of the piston 72 on the inner brake pad 2, and the outer brake pad 3 is pressed against the disc rotor D by the pair of

claw portions

60, 60. As a result, the disc rotor D is sandwiched between the pair of inner brake pads 2 and outer brake pads 3 to generate a frictional force, and further, a braking force of the vehicle is generated.

On the other hand, when the brake is released, the electric motor 56 is driven in accordance with a command from the control device 79, and the rotation in the brake release direction is transmitted to the rotation-to-linear motion conversion mechanism 75 via the speed reduction mechanism 74. Subsequently, the linear motion member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 retreats and returns to the initial position, and the piston 72 also retreats together with the linear motion member of the rotational linear motion conversion mechanism 75. As a result, the pressing force acting from the piston 72 to the inner brake pad 2 is released, and the braking force generated by the pair of inner brake pad 2 and outer brake pad 3 is released.

Therefore, when the brake is released, the control device 79 controls the driving force of the electric motor 56, and therefore the control device 79 controls the position of the linear motion member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 along the axial direction of the cylinder portion 59. In short, the control device 79 maintains the linear motion member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 in a state of retreating to its initial position and stopping.

The

elastic members

34, 34 are set to be larger than at least sliding resistance of the piston 72 against the cylinder bore 70 of the cylinder portion 59 and are set to be larger than sliding resistance of the slide pins 64, 64 connected to the cylinder portion 59 against the

pin insertion portions

8, 8 of the bracket 5. As a result, when the brake is released, the inner brake pad 2 and the outer brake pad 3 can be reliably retracted in the axial direction of the disc rotor D in a direction away from the disc rotor D by the urging forces of the

elastic members

34 and 34.

Even in a state where the piston 72 is not retracted to the initial position at the time of brake release, the piston 72 can be retracted with the inner brake pad 2 relative to the cylinder bore 70 by the biasing force of the

elastic members

34 and 34. At this time, the piston 72 is retracted relative to the cylinder bore 70 by the biasing force of the

elastic members

34 and 34, but the linear motion member (including the rotational linear motion member) retracted to the initial position of the rotational linear motion conversion mechanism 75 serves as a stopper, and therefore, the piston is stopped at the standard initial position without being further retracted. This prevents the piston 72 from returning excessively in the cylinder portion 59 due to the biasing force of the

elastic members

34 and 34, and thus does not cause a problem in response during braking operation.

Further, when the brake is released, the linear motion member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 is pressed in the backward direction via the piston 72 by the urging force of each of the elastic members 34, but since the urging force of each of the

elastic members

34, 34 is set to be smaller than the sliding resistance for operating the rotational linear motion conversion mechanism 75, the rotational member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 is not rotated in the backward direction, and the load on the electric motor 56 is suppressed.

As described above, the disc brake 1 according to the present embodiment includes the

elastic members

34 and 34 that urge the inner brake pad 2 and the outer brake pad 3 in the direction away from the disc rotor D in the axial direction of the disc rotor D, and the urging force of the elastic member 34 is set to be larger than the sliding resistance of the piston 72 with respect to the cylinder portion 59. As a result, even in a state where the piston 72 is not retracted to the initial position at the time of brake release, the piston 72 can be retracted to the initial position in the cylinder portion 59 particularly by the urging force of the pair of inner

elastic members

34 and 34. As a result, the inner brake pad 2 can be retracted, particularly together with the piston 72, in a direction away from the disc rotor D so as to overcome the sliding resistance between the piston 72 and the cylinder bore 70. This can suppress dragging of the inner brake pad 2 particularly by the biasing force of the pair of inner

elastic members

34 and 34.

In the disc brake 1 of the present embodiment, the urging force of each of the

elastic members

34, 34 is set to be larger than the sliding resistance of the cylinder portion 59 (slide pin 64) with respect to the bracket 5 (pin insertion portion 8). As a result, when the brake is released, the outer brake pad 3 is retracted in a direction away from the disc rotor D by the urging force of the outer pair of

elastic members

34 and 34, in particular. At this time, the slide pins 64 and 64 connected to the cylinder portion 59 can be retracted outward in the

pin insertion portions

8 and 8 of the bracket 5 via the pair of

claw portions

60 and 60 so as to overcome the sliding resistance with the

pin insertion portions

8 and 8. In this way, by returning to the initial position where they are opposed to each other between the slide pins 64, 64 of the cylinder portion 59 and the

pin insertion portions

8, 8 of the bracket 5, the outer brake pad 3 can be retracted particularly in a direction away from the disc rotor D. This can suppress dragging of the outer brake pad 3 particularly by the urging force of the outer pair of

elastic members

34, 34.

Further, in the disc brake 1 of the present embodiment, since the

elastic members

34 and 34 are provided, it is not necessary to retract the linear motion member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 and the piston 72 by a relatively long distance in consideration of the clearance (assembly play) between the components of the rotational linear motion conversion mechanism 75, and it is possible to retract the piston 72 by a minimum distance, and it is possible to improve the response of the braking operation. Further, the gap (assembly play) between the rotation-to-linear motion conversion mechanism 75 and the piston 72 including the gap (assembly play) between the respective components of the rotation-to-linear motion conversion mechanism 75 can be absorbed by the urging force of the respective elastic members 34, and the responsiveness of the braking operation can be improved.

In the disc brake 1 of the present embodiment, the urging force of each of the

elastic members

34, 34 is set to be smaller than the sliding resistance for operating the rotation-to-linear conversion mechanism 75. As a result, when the linear motion member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75 is pressed in the backward direction via the piston 72 by the biasing force of the

elastic members

34 and 34, the load on the electric motor 56 can be suppressed without applying rotation in the backward direction to the rotation member (including the rotational linear motion member) of the rotational linear motion conversion mechanism 75.

In the disc brake 1 of the present embodiment, the urging force of each of the

elastic members

34, 34 is set to be larger than the sliding resistance obtained by adding the sliding resistance of the piston 72 with respect to the cylinder bore 70 to the sliding resistance of the inner brake pad 2 and the outer brake pad 3 with respect to the inner arm portion 14 and the outer arm portion 17. As a result, when the braking is released, the inner brake pad 2 and the outer brake pad 3 can be smoothly retreated in the axial direction of the disc rotor D in the direction away from the disc rotor D by the biasing force of the

elastic members

34 and 34, and the drag of the inner brake pad 2 and the outer brake pad 3 can be reliably suppressed.

In the disc brake 1 of the present embodiment, the urging force of each of the

elastic members

34, 34 may be set to be smaller than the sliding resistance of the piston 72 with respect to the cylinder portion 59 and larger than a force obtained by adding the sliding resistance of the inner brake pad 2 and the outer brake pad 3 with respect to the inner arm portion 14 and the outer arm portion 17 of the bracket 5 and the sliding resistance of each of the slide pins 64, 64 connected to the cylinder portion 59 with respect to each of the

pin insertion portions

8, 8 of the bracket 5. In this case, although the piston 72 cannot be slid and retreated with respect to the cylinder portion 59 (cylinder bore 70) by the biasing force of each of the elastic members 34, the caliper 4 and the inner and

outer brake pads

2, 3 can be retreated with respect to the carrier 5 in the direction in which the inner and

outer brake pads

2, 3 are separated from the disc rotor D, and as a result, dragging of the inner and

outer brake pads

2, 3 can be suppressed.

Further, in the disc brake 1 of the present embodiment, the pair of inner

elastic members

34, 34 are provided between the inner support portion 9 of the carrier 5 and the inner brake pad 2, while the pair of outer

elastic members

34, 34 are provided between the outer support portion 10 of the carrier 5 and the outer brake pad 3, so that the structure for suppressing drag of the inner brake pad 2 and the outer brake pad 3 can be simplified.

As the disc brake 1 according to the embodiment described above, for example, the following embodiments can be considered.

In a first aspect, the present invention provides a disc brake including: a brake mechanism (76) that pushes a piston (72) in a cylinder (59) by driving an electric motor (56), and applies a braking force by pressing pads (2, 3) against a disc rotor (D); and an elastic member (34), wherein the elastic member (34) biases the pads (2, 3) in a direction away from the disc rotor (D) in the axial direction of the disc rotor (D), and the biasing force of the elastic member (34) is greater than the sliding resistance of the piston (72) with respect to the cylinder (59).

In a second aspect, in the first aspect, the piston (72) is configured to be advanced in the cylinder (59) by an operation of a rotation-to-linear motion conversion mechanism (75) to which a driving force of the electric motor (56) is transmitted, and an urging force of the elastic member (34) is smaller than a sliding resistance for operating the rotation-to-linear motion conversion mechanism (75).

In a third aspect, in the first or second aspect, the pads (2, 3) are slidably supported by a mounting member (5), the mounting member (5) is mounted to a non-rotating portion of a vehicle, and the force of the elastic member (34) is larger than a force obtained by adding a sliding resistance of the piston (72) with respect to the cylinder portion (59) and a sliding resistance of the pads (2, 3) with respect to the mounting member (5).

In a fourth aspect, in any one of the first to third aspects, the cylinder section (59) is slidably supported by an attachment member (5), the attachment member (5) is attached to a non-rotating portion of a vehicle, and the force of the elastic member (34) is greater than the sliding resistance of the cylinder section (59) with respect to the attachment member (5).

In a fifth aspect, in any one of the first to fourth aspects, the elastic member (34) is provided between a mounting member (5) mounted to a non-rotating portion of a vehicle and the pads (2, 3).

In a sixth aspect, the present invention provides a disc brake including: a brake mechanism (76) that has a mounting member (5) and a caliper (4), wherein the mounting member (5) supports sliding of the pads (2, 3) and is mounted to a non-rotating portion of the vehicle, wherein the caliper (4) has a cylinder portion (59) and is supported so as to be slidable in the axial direction of the disc rotor (D) with respect to the mounting member (5), and wherein the brake mechanism (76) applies a braking force by pressing the pads (2, 3) against the disc rotor (D) by means of a piston (72) that slides in the cylinder portion (59); and an elastic member (34) that biases the pads (2, 3) in a direction away from the disc rotor (D) in the axial direction of the disc rotor (D), wherein the force of the elastic member (34) is smaller than the sliding resistance of the piston (72) with respect to the cylinder (59) and is larger than a force obtained by adding the sliding resistance of the pads (2, 3) with respect to the mounting member (5) and the sliding resistance of the caliper (4) with respect to the mounting member (5).

The present invention is not limited to the above embodiment, and includes various modifications. For example, the above embodiments have been described in detail to explain the present invention in an easily understandable manner, but the present invention is not limited to having all the configurations described above. Note that a part of the structure of one embodiment may be replaced with the structure of another embodiment, or the structure of one embodiment may be added to the structure of another embodiment. In addition, as for a part of the configuration of each embodiment, addition, deletion, and replacement of another configuration can be performed.

The present application claims priority from japanese patent application No. 2019-234340, filed on 25.12.2019. The entire disclosure including the specification, claims, drawings and abstract of japanese patent application No. 2019-234340, filed 2019, 12, 25, is incorporated by reference in its entirety.

Description of the reference numerals

1 disc brake, 2 inner brake pads (pads), 3 outer brake pads (pads), 4 caliper, 5 carrier (mounting member), 34 elastic member, 56 electric motor, 59 cylinder portion, 72 piston, 75 rotation-translation conversion mechanism, 76 brake mechanism, D disc rotor.

Claims

1. A disk brake, characterized in that,

the disc brake includes:

a brake mechanism that pushes a piston in a cylinder portion by driving of an electric motor and applies a braking force by pressing a pad against a disc rotor; and

an elastic member that urges the pad in a direction away from the disc rotor in an axial direction of the disc rotor,

the force of the elastic member is larger than the sliding resistance of the piston with respect to the cylinder portion.

2. The disc brake of claim 1,

the piston is configured to be advanced in the cylinder by operation of a rotation-to-linear conversion mechanism to which a driving force of the electric motor is transmitted,

the force of the elastic member is smaller than the sliding resistance for operating the rotation-to-linear motion conversion mechanism.

3. The disc brake of claim 1 or 2,

the pad is slidably supported by a mounting member mounted to a non-rotating portion of the vehicle,

the elastic member has a larger force than a force obtained by adding a sliding resistance of the piston with respect to the cylinder portion and a sliding resistance of the pad with respect to the attachment member.

4. A disc brake according to any one of claims 1 to 3,

the cylinder portion is slidably supported by a mounting member attached to a non-rotating portion of a vehicle,

the force of the elastic member is larger than the sliding resistance of the cylinder portion with respect to the mounting member.

5. The disc brake of any one of claims 1 to 4,

the elastic member is provided between a mounting member mounted to a non-rotating portion of a vehicle and the pad.

6. A disk brake, characterized in that,

the disc brake includes:

a brake mechanism including a mounting member that supports sliding of a pad and is mounted to a non-rotating portion of a vehicle, and a caliper that has a cylinder portion and is supported so as to be slidable in an axial direction of a disc rotor with respect to the mounting member, the brake mechanism pressing the pad against the disc rotor by a piston that slides in the cylinder portion to apply a braking force; and

the elastic member has a force smaller than a sliding resistance of the piston with respect to the cylinder portion and larger than a force obtained by adding a sliding resistance of the pad with respect to the mounting member and a sliding resistance of the caliper with respect to the mounting member.